1. Field of the Invention
This invention relates to methods for isolating polyphenylene ether polymer resins from solution in a single pass from a wiped thin-film evaporator.
2. Brief Description of Related Art
Methods for removing organic solvents from thermoplastic resins using wiped thin film evaporators are disclosed in U.S. Pat. Nos. 5,419,810, 5,573,635, 4,065,346 and 5,256,250. It would be desirable to operate the device under high temperature conditions, which removes substantially all solvent from polyphenylene ether polymer resins in a single pass. This is not practical where the heat necessary to achieve such a result can pyrolize or thermally decompose the polyphenylene ether polymers, forming volatile by-products as well as non-volatile by-products. The formation of such by-products reduces the yield and/or product quality.
It is desirable to provide a method which allows for polyphenylene ether polymer resins to be isolated from solution and substantially free of solvents in a single pass of wiped thin film evaporator without significant degradation of the polyphenylene ether polymer resins. It is also desirable to maximize the throughput of wiped thin film evaporators operating under conditions which remove substantially all organic solvents from a solution of polyphenylene ether polymer resins without the significant degradation of the polyphenylene ether polymer resins.